Viral gastroenteritis

Question 1

What is viral gastroenteritis?

Answer 1

Acute inflammation of the lining of the stomach and intestines caused by enteropathogenic (the gastrointestinal system is the principal site of infection) viruses

Question 2

What can cause viral gastroenteritis?

Answer 2

Causative Organisms → norovirus > sapovirus > rotavirus
Rotavirus: most common cause of infantile gastroenteritis
Norovirus: most common cause of viral infectious gastroenteritis in all ages in England and Wales
Adenoviruses: commonly cause infections of the respiratory system but can also cause gastroenteritis, particularly in children.

Bacterial Causes ⇒
Staphylococcus aureus: usually found in cooked meats and cream products.
Bacillus cereus: mainly found in reheated rice.
Clostridium perfringens: usually found in reheated meat dishes or cooked meats.
Campylobacter
E.coli including E.coli 0157 (which can cause haemolytic uraemic syndrome)
Salmonella
Shigella

Question 3

What are the risk factors for viral gastroenteritis?

Answer 3

Risk Factors → exposure to contaminated food, close contact with infected people, poor hygeine, extremes of age, immunocompromise

Question 4

What are the presenting symptoms/ signs of viral gastroenteritis?

Answer 4

Norovirus = abrupt onset, usually short lived GI upset 24-48 hours after innoculation. Typically self limiting in healthy people but can cause pre-renal acute kidney injury in the frail. Prevention involves strict handwashing with soap and warm water to prevent spread.

• Sudden-Onset Diarrhoea
• Blood or Mucus in Stool
• Vomiting
• Nausea
• Abdominal Pain
• Fever and Malaise
• Signs of dehydration o/e → mucous membranes, skin turgor, cap refill, urine output

Question 5

What investigation are used to diagnose/ monitor viral gastroenteritis?

Answer 5

1. FBC → required if starting IV fluids
2. U&Es → any diarrhoeal condition can lead to dehydration hence important to monitor
3. Stool Viral Culture → identifies viral pathogens

Question 6

How is viral gastroenteritis managed?

Answer 6

1. No Systemic Signs → bed rest, fluids and electrolyte replacement with oral rehydration therapy
2. Systemic Signs → admit + IV fluids + stool culture
3. C.difficile ⇒ oral vancomycin (add on IV metranidazole if severe)
   - C.diff = gram positive rod

Question 7

What complications may arise from viral gastroenteritis?

Answer 7

Guillain-Barre Syndrome
- Acute autoimmune demyelinating polyneuropathy affecting the PNS
- 30% of cases occur after gastroenteritis infection caused by campylobacter jejuni
- Sx ⇒ back/leg pain in intial stages of illness, ascending weakness, paraesthesia and pain (ie. legs are first) + areflexia (COMLETELY ABSENT)
- Can progress to affect respiratory muscles leading to respiratory failure and death (hence spirometry is important to monitor respiratory weakness)
- Diagnosis ⇒ CSF (Lumbar Puncture) will show high protein + normal WCC (autoimmune condition, antibodies are proteins, hence increased proteins). Nerve conduction studies = decreased motor nerve conduction due to demyelination.
- If suspected, admit immediately to hospital for further investigation
- Mx = IV immunoglobulins (normal antibodies to dilute autoantibodies) and plasmapheresis (filter antibodies out of plasma)